A method of knitting the knitted fabric having a double tubular structure in cross section by a flat knitting machine includes those disclosed in patent document 1 and patent document 2, for example.
According to the knitting method disclosed in patent document 1, knitting is performed in a manner that front and back knitted fabric parts of ribs, cuffs, and neckline of a sweater have double structure respectively in longitudinal section and a double tubular shape respectively in cross section. In the knitting method described in patent document 1, the inner tubular section and the outer tubular section are alternately knitted using one yarn feeder.
According to the knitting method disclosed in patent document 2, one part of the set up portion remains being held on a needle bed without knitting, and the set up portion is joined in the middle of the knitted fabric after knitting the knitted fabric in a tubular shape to a predetermined length. By knitting in this way, a pipe shaped portion is formed at the lower end of the tubular part, and a double tubular shape is formed in cross section.
Patent document 1: Japanese Patent No. 2514489
Patent document 2: Japanese Patent No. 3494487